You do not need permanent COO to succeed.
COO is inherently an interim job.
- New thoughts, ideas and skills build change momentum. Change is what you hired your COO to do.
- COO systematises and automates. So the job's final outcome should be becoming dispensable.
- Your company will be in a different state after the engagement. With interim COO, you get the opportunity to ask: is the COO best for the new reality (then renew!), or is it better to plan for a handover to someone else?
6 to 24 months is more than enough to make an impact.